Limited use data storing device

ABSTRACT

Embodiments of methods and systems for controlling access to information stored on memory or data storage devices are disclosed. In various embodiments, methods of retrieving information from a data storage device previously deactivated by modification or degradation of at least a portion of the data storage device are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is related to, claims the earliest availableeffective filing date(s) from (e.g., claims earliest available prioritydates for other than provisional patent applications; claims benefitsunder 35 USC §119(e) for provisional patent applications), andincorporates by reference in its entirety all subject matter of thefollowing listed application(s) (the “Related Applications”) to theextent such subject matter is not inconsistent herewith; the presentapplication also claims the earliest available effective filing date(s)from, and also incorporates by reference in its entirety all subjectmatter of any and all parent, grandparent, great-grandparent, etc.applications of the Related Application(s) to the extent such subjectmatter is not inconsistent herewith. The United States Patent Office(USPTO) has published a notice to the effect that the USPTO's computerprograms require that patent applicants reference both a serial numberand indicate whether an application is a continuation orcontinuation-in-part. The present applicant entity has provided below aspecific reference to the application(s) from which priority is beingclaimed as recited by statute. Applicant entity understands that thestatute is unambiguous in its specific reference language and does notrequire either a serial number or any characterization such as“continuation” or “continuation-in-part.” Notwithstanding the foregoing,applicant entity understands that the USPTO's computer programs havecertain data entry requirements, and hence applicant entity isdesignating the present application as a continuation-in-part of itsparent applications, but expressly points out that such designations arenot to be construed in any way as any type of commentary and/oradmission as to whether or not the present application contains any newmatter in addition to the matter of its parent application(s).

RELATED APPLICATIONS

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/124,924 entitled METHOD AND SYSTEM FOR FLUIDMEDIATED DISK ACTIVATION AND DEACTIVATION, naming BRAN FERREN, ELEANORV. GOODALL, AND EDWARD K. Y. JUNG as inventors, filed 9 May 2005 nowU.S. Pat. No. 7,596,073, which is currently co-pending, or is anapplication of which a currently co-pending application is entitled tothe benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/124,923 entitled FLUID MEDIATED DISK ACTIVATIONAND DEACTIVATION MECHANISMS, naming BRAN FERREN, ELEANOR V. GOODALL, ANDEDWARD K. Y. JUNG as inventors, filed 9 May 2005 now U.S. Pat. No.7,519,980, which is currently co-pending, or is an application of whicha currently co-pending application is entitled to the benefit of thefiling date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/150,823 entitled ROTATION RESPONSIVE DISKACTIVATION AND DEACTIVATION MECHANISMS, naming BRAN FERREN, EDWARD K. Y.JUNG AND CLARENCE T. TEGREENE as inventors, filed 9 Jun. 2005 now U.S.Pat. No. 7,668,068, which is currently co-pending, or is an applicationof which a currently co-pending application is entitled to the benefitof the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/150,837 entitled METHOD AND SYSTEM FORROTATIONAL CONTROL OF DATA STORAGE DEVICES, naming BRAN FERREN, EDWARDK. Y. JUNG AND CLARENCE T. TEGREENE as inventors, filed 9 Jun. 2005 nowU.S. Pat. No. 7,916,615, which is currently co-pending, or is anapplication of which a currently co-pending application is entitled tothe benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/198,939 entitled MEMORY DEVICE ACTIVATION ANDDEACTIVATION, naming BRAN FERREN AND EDWARD K. Y. JUNG as inventors,filed 5 Aug. 2005, which is currently co-pending, or is an applicationof which a currently co-pending application is entitled to the benefitof the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/198,938 entitled LIMITED USE MEMORY DEVICE WITHASSOCIATED INFORMATION, naming BRAN FERREN AND EDWARD K. Y. JUNG asinventors, filed 5 Aug. 2005 now U.S. Pat. No. 7,668,069, which iscurrently co-pending, or is an application of which a currentlyco-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/223,829 entitled METHOD OF MANUFACTURING ALIMITED USE DATA STORING DEVICE, naming BRAN FERREN AND EDWARD K. Y.JUNG as inventors, filed Sep. 9, 2005 substantially herewith, which iscurrently co-pending, or is an application of which a currentlyco-pending application is entitled to the benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/223,898 entitled DATA RETRIEVAL METHODS namingBRAN FERREN AND EDWARD K. Y. JUNG as inventors, filed Sep. 9, 2005substantially herewith, which is currently co-pending, or is anapplication of which a currently co-pending application is entitled tothe benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/223,888 entitled DATA RETRIEVAL SYSTEMS namingBRAN FERREN AND EDWARD K. Y. JUNG as inventors, filed Sep. 9, 2005substantially herewith, which is currently co-pending, or is anapplication of which a currently co-pending application is entitled tothe benefit of the filing date.

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/223,899 entitled LIMITED USE DATA STORING DEVICEnaming BRAN FERREN AND EDWARD K. Y. JUNG as inventors, filed 9 Sep.,2005 now U.S. Pat. No. 7,770,028, which is currently co-pending, or isan application of which a currently co-pending application is entitledto the benefit of the filing date.

BACKGROUND

Various methods have been used to control access to information storedon data storage devices such as CDs, DVDs, floppy disks, and so forth.Methods of controlling access to information are utilized for variousreasons including, for example, to limit unauthorized access tocopyrighted information. Such methods may involve requiring the use ofaccess codes provided, e.g., on data storage device packaging in orderto read information from a data storage device, or erasing data orpreventing reading of data from a data storage device following readingof the device.

SUMMARY

Embodiments of devices, methods and systems relating to retrieval ofinformation from deactivated, expired or disabled memory or data storagedevices are disclosed. Features of various embodiments will be apparentfrom the following detailed description and associated drawings.

BRIEF DESCRIPTION OF THE FIGURES

Features of the invention are set forth in the appended claims. Theexemplary embodiments may best be understood by making reference to thefollowing description taken in conjunction with the accompanyingdrawings. In the figures, like referenced numerals identify likeelements.

FIG. 1 is a block diagram of a system including a data storage device;

FIG. 2 illustrates a computer system;

FIG. 3 illustrates a disk including stored machine readable data andindex information;

FIG. 4 illustrates a disk including stored machine readable data and keyinformation;

FIG. 5 is a schematic diagram of an embodiment of a system foractivation of a deactivated data storage device;

FIG. 6 is a schematic diagram of another embodiment of a system foractivation of a deactivated data storage device;

FIG. 7 is a flow diagram of a process including retrieval ofread-support information;

FIG. 8 is a schematic diagram illustrating exemplary processes forreading data from a data storage device;

FIG. 9A illustrates an original set of machine readable data;

FIGS. 9B-9H illustrate different degraded forms of the machine readabledata depicted in FIG. 9A;

FIG. 10A depicts in schematic form data stored in a data storage mediumon a substrate;

FIG. 10B depicts the embodiment of FIG. 10A following degradation of thesubstrate;

FIG. 10C depicts the embodiment of FIG. 10A following degradation of thedata;

FIG. 10D depicts the embodiment of FIG. 10A following degradation of thedata storage medium;

FIG. 11 illustrates a data storage device with read-support information;

FIG. 12 illustrates a data storage device with degraded read-supportinformation;

FIG. 13 illustrates a data storage device with partially degradedread-support information;

FIG. 14 illustrates a data storage device with partially degradedread-support information;

FIG. 15A illustrates a data storage device including primary andsecondary read-support information;

FIG. 15B illustrates the device of FIG. 15A following degradation of theprimary read-support information;

FIG. 16 depicts a data storage device including read-support informationdispersed in the data of interest;

FIG. 17 is a flow diagram of a method of retrieving information from adeactivated memory device;

FIG. 18 depicts a further exemplary method of retrieving informationfrom a deactivated memory device;

FIG. 19 depicts another exemplary method of retrieving information froma deactivated memory device;

FIG. 20 depicts another exemplary method of retrieving information froma deactivated memory device;

FIG. 21 depicts an embodiment of a method of reactivating a deactivatedmemory device, including variations thereof;

FIG. 22 is a flow diagram of a method of retrieving data from an expiredlimited use memory device;

FIG. 23 depicts a further embodiment of a method of retrieving data froman expired limited use memory device;

FIG. 24 depicts another embodiment of a method of retrieving data froman expired limited use memory device;

FIG. 25 is a flow diagram of an embodiment of a method of manufacturinga limited use memory device;

FIG. 26 is a flow diagram of a further embodiment of a method ofmanufacturing a limited use memory device;

FIG. 27 is a flow diagram of a further embodiment of a method ofmanufacturing a limited use memory device;

FIG. 28 depicts an example of multiple batches of data storage devicesand associated data storage device identification codes;

FIG. 29 depicts a further variant of a method of manufacturing a limiteduse memory device;

FIG. 30 depicts another variant of a method of manufacturing a limiteduse memory device;

FIG. 31 is a flow diagram of a method of manufacturing a limited usememory device, including variants thereof;

FIG. 32 is a flow diagram of an exemplary method of configuring alimited use memory device;

FIG. 33 is a flow diagram showing variants of a method of configuring alimited use memory device;

FIG. 34A depicts reading of data from an intact data storage device witha first read device;

FIG. 34B depicts reading of data from a deactivated data storage devicewith a first read device;

FIG. 34C depicts reading of data from a deactivated data storage devicewith a second read device;

FIG. 35 illustrates a data storage device including read-control dataand two data portions;

FIG. 36 illustrates a data storage device including secondaryread-support information;

FIG. 37 is a cross-sectional view of a data storage device includingdata stored at two spatial frequencies;

FIG. 38 is a flow diagram of a method of manufacturing a memory device;

FIG. 39 depicts a data storage device including multiple copies ofread-support information;

FIG. 40 depicts a data storage device including read-support informationincluding redundancies;

FIG. 41 depicts the data storage device of FIG. 40 following reductionof redundancy in the read-support information;

FIG. 42 illustrate a data storage medium having data stored at severaldifferent levels;

FIG. 43 is a flow diagram of an exemplary method of manufacturing a datastorage device;

FIG. 44 is a flow diagram of an exemplary method of configuring a memorydevice;

FIG. 45 is a flow diagram of an exemplary method of retrieving data froman expired limited use memory device;

FIG. 46 is a flow diagram of a further exemplary method of retrievingdata from an expired limited use memory device;

FIG. 47 is a flow diagram of a further exemplary method of retrievingdata from an expired limited use memory device; and

FIG. 48 depicts a read device including a read heard having twodifferent types of sensors.

DETAILED DESCRIPTION

Data storage devices may be used to store a wide variety of types ofdata of interest including audio data, video data, text data, graphicaldata, numerical data, and software code, to name only a few examples. Insome cases, it may be desired to permit reading of data from a datastorage device for a limited period of time or for a limited number ofuses or reads of the device. Such cases arise, for example, when acopyright holder wishes to limit access to copyrighted data, e.g. topermit software to be installed on a limited number of computer systems,or to permit a ‘rented’ movie to be viewed over the course of a few daysand not longer. Limiting number of reads or duration of access toinformation may be of utility in various other applications as well,including, but not limited to, the distribution of information that isconfidential or information that is valid for only a limited period oftime. As used herein, the term “data of interest” refers to some portionof the data stored on a data storage device that is of interest withregard to controlling access to the data. It is not intended that thedata of interest must include all data on the data storage device thatmight be of use or of interest to a user of the data storage device. Insome embodiments, the data of interest may include all or the majorityof useable data on the data storage device, while in others it mayinclude only a subset of the useable data on the data storage device. Insome embodiments, the data of interest may include selected modules ofcomputer program code, or selected portions of a video or audiorecording, so that access to certain portions of the program, video, oraudio recording (for example) may be restricted, while other portionsmay remain accessible, or become accessible.

In some cases it may be desirable to provide the user of a data storagedevice the possibility of regaining access to information on the datastorage device after deactivation of the data storage device. Accordingto various embodiments as exemplified herein, methods, systems anddevices are provided for retrieving information from degraded ordeactivated data storage devices. Examples of data storage devices thatmay be usable for a limited number of uses (or reads) or for a limitedperiod of time and subsequently modified, degraded or deactivated todestroy or render inaccessible or unusable some or all data on the datastorage device are disclosed and described in U.S. patent applicationSer. No. 11/124,924, filed May 9, 2005, entitled METHOD AND SYSTEM FORFLUID MEDIATED DISK ACTIVATION AND DEACTIVATION; U.S. patent applicationSer. No. 11/124,923, filed May 9, 2005, entitled FLUID MEDIATED DISKACTIVATION AND DEACTIVATION MECHANISMS; U.S. patent application Ser. No.11/150,823 filed Jun. 9, 2005, entitled ROTATION RESPONSIVE DISKACTIVATION AND DEACTIVATION MECHANISMS; U.S. patent application Ser. No.11/150,837, filed Jun. 9, 2005, entitled METHOD AND SYSTEM FORROTATIONAL CONTROL OF DATA STORAGE DEVICES; U.S. patent application Ser.No. 11/198,939, filed Aug. 5, 2005, entitled MEMORY DEVICE ACTIVATIONAND DEACTIVATION and U.S. patent application Ser. No. 11/198,938, filedAug. 5, 2005, entitled LIMITED USE MEMORY DEVICE WITH ASSOCIATEDINFORMATION, to which the present application claims priority, and whichare incorporated herein by reference in their entirety, and U.S. Pat.Nos. 6,011,772; 6,228,440; 6,709,802; 6,780,564; 6,838,144; 6,839,316;all of which are incorporated herein by reference in their entirety.

FIG. 1 illustrates a system 10, which may be a computer system or othersystem that includes a read device 12 adapted for reading machinereadable data from data storage device 14. Data storage device 14 mayinclude a modifiable or degradable portion 17 that prior to degradationor modification contains information that supports reading ofinformation from a portion of data storage device 14. As will bediscussed herein, and as discussed in various references incorporatedherein by reference, data storage devices according to variousembodiments may include features that render at least portions of thedata storage device degradable under certain conditions. In addition tocomputers, exemplary embodiments of systems that may include readdevices for reading data from a data storage device included DVDplayers, CD players, card readers, and various special purpose devicesfor reading any sort of image, audio, text, software, or other data froma data storage device. System 10 may include a processor 16, systemmemory 18, one or more I/O devices 20, and data bus 22. Data and controlsignals may be transferred between system components via data bus 22.System memory 18 may include read-only memory (ROM) 24 and random accessmemory (RAM) 26. During use, device driver software 30 may be stored inRAM 26. System 10 may also include a power supply, not shown. Processor16 may be a microprocessor, for example. Data storage device 14 may be aCD, DVD, floppy disk, smart card, magnetic stripe card, magnetic tape,or any of various other data storage devices capable of storing machinereadable data. In this and other embodiments, data storage devices maytake the form of disks, cards, or microchips, for example. System 10 mayinclude a read device interface 32 operatively connected between readdevice 12 and system bus 22.

FIG. 2 depicts a specific example of a system as depicted in FIG. 1.FIG. 2 illustrates a computer system 50. Computer system 50 may includea microprocessor 52, system memory 54, system bus 56, output device 58,and input device 60. In this example output device 58 is a monitor. Oneor multiple output devices of other types may be used in variousembodiments, including but not limited to speakers, printers, datastorage devices, and audio, video, or tactile displays of various types.Similarly, input device 60 in the present example is a keyboard, butother types of input devices, including but not limited to, computermice, track balls, touch screens, microphones, scanners, may be usedinstead, either singly or in combination. System memory 54 includesread-only memory 62 and random-access memory 64. Device driver 66 may bestored in random-access memory 64. Device driver 66 is used to controldisc drive 70. Drive Interface 72 provides an interface between thecomputer system 50 and disk drive 70. Control line 74 and data line 76provide for the transfer of control and data signals between system 50and disk drive 70. Disk drive 70 includes receptacle 78, which isadapted to receive disk 80. Disk 80 is rotated by motor 82. Positioner84 adjusts the position of the read head 86 with respect to disk 80.

Systems for reading data from such data storage devices may includegeneral-purpose computing devices and other systems having thecapability of reading data from data storage devices. Such systems mayexpose data storage devices to influences that produce degradation ormodification in the data storage device. For example a system such ascomputer system 50 may include hardware or software that cause light ofa particular intensity or wavelength to be directed to a particularregion of a data storage device when it is in the read device, cause thedata storage device to be subjected to a spin of a specified intensityor duration by the read device, or cause the data storage device to beexposed to a particular electrical field or magnetic field strength. Insome embodiments, the data storage device (e.g., disk 80) may beconfigured so that some or all of it will be modified or inactivatedfollowing a selected number of uses. In some embodiments, components ofsystem 50 may operate in a conventional manner. In other embodiments,selected components of system 50 may include features that arespecialized to produce modification or degradation of the data storagedevice. For example, if a portion of disk 80 is degraded by exposure tohigh intensity light, disk drive 70 may be modified to direct highintensity light onto an appropriate portion of disk 80 to causedeactivation of disk 80. System 50 may be modified at the level of drive70, drive interface 72, or program code 66 residing in RAM 64. Drive 70or drive interface 72 may be modified at the hardware, firmware orsoftware level. Program code 66 may be system software or applicationprogram software. System 50 may be configured to detect prior activationof a rotation activatable mechanism on data storage device 80 based upondetection of a modification to data storage device 80. Modifications todata storage device 80 associated with prior activation may be detectedby various means. If the modification includes modification of data ormodification of accessibility of a particular portion of data, themodification may be detected when an attempt is made to read data fromdata storage device 80, e.g. by failure of reading. Such modificationsmay be manifested as modifications of data or accessibility of data, butare not limited to modification of data or data accessibility. In someembodiments, modifications may be detectable by optical, electrical,magnetic, or other means, and the presence of the modification may serveas an instruction to the system to discontinue reading of the disk, orto operate in a specified manner (e.g., by increasing the speed ofrotation of the disk, delivering light to a selected region of the disk,etc.). Combinations of data read devices and data storage devices thatmay be used to produce data storage device deactivation are described,for example, in U.S. Pat. Nos. 6,011,772; 6,228,440; 6,709,802;6,744,551; 6,780,564; 6,838,144; and 6,839,316.

FIG. 3 depicts an embodiment of an exemplary data storage device. Asdepicted in FIG. 3, data of interest (for example, a computer program oran audio or video digital recording) may be distributed to multiplelocations on data storage device 100 (which in this example is depictedas a disk, but which may take other forms, as well). In order toretrieve the data of interest in usable form, it may be from theappropriate location in the appropriate order, as specified by indexinformation stored in index region 102. In the present exemplaryembodiment, index region 102 may specify that data may be read fromfirst data region 104, second data region 106, third data region 108,fourth data region 110, fifth data region 112 and sixth data region 114,in that sequence. Thus, in order to render the data stored in firstthrough sixth data regions 104 through 114 unusable, it may besufficient to render data stored in index region 102 inaccessible, eventhough the data contained in data segments 104, 106, 108, 110, 112, and114 may still be intact and otherwise readable. Therefore, according tocertain embodiments, a data storage device deactivated in this way canbe ‘reactivated’ by providing the index information from another source.

A further exemplary data storage device is depicted in FIG. 4. In FIG.4, a data storage device 150 may include data of interest in data region152 stored in encrypted or encoded form, and key information stored inkey region 154. Key information stored in key region 154 is used todecode or decrypt data of interest stored in data region 152. Asdescribed in connection with the embodiment shown in FIG. 3, if keyinformation in key region 154 is destroyed, modified, or renderedinaccessible, the data of interest contained in data region 152 may berendered inaccessible even though the data is still intact and readable.Thus, a data storage device deactivated in this way can be ‘reactivated’by providing the data read device with key information from anothersource.

Both index information used in the embodiment of FIG. 3 and keyinformation used in the embodiment of FIG. 4 may be classified generallyas ‘read-support information’. Other forms of ordering, encoding,encrypting or otherwise structuring data so that it is readable onlywith the use of some form of read-support information may be used invarious embodiments as disclosed herein, and the term read-supportinformation is not intended to be limited only to key and indexinformation as illustrated in FIGS. 3 and 4. Methods of encoding orencrypting data are known or may be developed by those of skill in therelevant arts, and the embodiments described herein are not limited touse with any particular data indexing, encoding or encryption scheme.Encryption methods may include public key encryption methods such asDiff-Hellman, RSA, EIGaml, DSS, Elliptic curve, Paillier cryptosystem,or Password-authenticated Key agreement encryption method, or a privatekey encryption method, such as a DES encryption method.

FIG. 5 is a schematic diagram of an embodiment of a system 158 foractivation of a data storage device 160. System 158 includes read devicecontaining system 168 (which may be, for example, a computer system, aDVD player, a CD player, or various other systems that include a readdevice capable of reading data from a data storage device) and remotesystem 170. Data storage device 160 includes data storage deviceidentification code 162, data of interest 164, and, prior tomodification of the device (e.g., in connection with use of the device),read-support information 166. Read device containing system 168 makesuse of read-support information 166 on data storage device 160 to readdata of interest 164 from data storage device 160. Following degradationor modification of data storage device 160, in which read-supportinformation 166 is degraded, modified, or otherwise renderedinaccessible, data of interest 164 remains intact but cannot be read (orcannot be read in a useful format) from data storage device 160.According to use of system 158, read device containing system 168 maysend a request to remote system 170, the request including at least datastorage device identification code 162. The data storage deviceidentification code 162 is matched to a device ID code 172 with remotesystem 170, and a corresponding override code 173 is identified. Theoverride code is then provided to read device containing system 168 byremote system 170. Device ID code 172 and override code 173 areassociated, linked, or correlated with each other in remote system 170.Remote system 170 may be a hardware and/or software based system, andthe request and override code may be transmitted between read devicecontaining system 168 and remote system 170 in electronic format, via awireless transmission, or via other methods for machine communication.Transfer of request and the override code may be performed in anautomated fashion under hardware or software control, or under thedirection of a user of a read device containing system 168. For example,remote system 170 may include a web site (e.g., a service or support website), and device ID code 172 and override code 173 may be transmittedelectronically to/from the web site. The override code may contain anydata or information sufficient to override the deactivation of datastorage device 160 to enable reading of data of interest 164 from datastorage device 160. Override code 173 may include read-supportinformation necessary to permit data to be read from a deactivatedmemory or data storage device. Override code 173 may be a backup copy ofsome or all of read-support information 166. In some embodiments,override code 173 may be an analog of read-support information 166,i.e., it may be functionally equivalent to read-support information 166with regard to enabling reading of data of interest from data storagedevice 160, but it may not be exactly the same as read-supportinformation 166. Remote system 170 may be at a location distinct fromread device containing system 168. In some embodiments, remote system170 may be operated by a third party or service provider.

FIG. 6 is a schematic diagram of another embodiment of a system foractivation of a deactivated data storage device 160. In the embodimentof FIG. 6, as in the embodiment of FIG. 5, data storage device 160 isused in connection with read device containing system 168. Similarly, aremote system 170 includes linked or associated device ID code 172 andoverride code 173. In the embodiment of FIG. 6, however, communicationbetween read device containing system 168 and remote system 170 isperformed via user 174 of data storage device 160 and a human operator175 of remote system 170. Communication between user 174 and operator175 may be carried out in-person, via telephone, e-mail, or by variousother forms of human communication as are well-known or as may bedeveloped in the future. User 174 may be the usual user (e.g. the owneror licensee) of data storage device 160, or user 174 may be arepresentative of the usual user of data storage device 160, including,but not limited to, an employee of a service shop. Operator 175 may bean employee of a service shop, an employee or contractor of the sellerof the data storage device or data stored on the data storage device,for example. Remote system 170 may be a computer-based system, in whichoperator 175 may access an override code stored in a machine readableformat accessible to remote system 170. Alternatively, remote system 170may include various other systems for storing an override code 173 inassociation with a device ID code 172, including, for examplealphanumeric codes stored in a table printed on a sheet of paper in aformat readable by operator 175.

Either an automated system including remote system 170, as shown in FIG.5, or a system that includes a human intermediary, as shown in FIG. 6,may be considered a support entity. Accessing of read-supportinformation may be handled automatically by the system reading the dataand thus be transparent to the user of the system unless the device isdeactivated to prevent reading of data.

FIG. 7 is a flow diagram of a process including retrieval ofread-support information. The process of FIG. 7 may occur at the initialreading of data from a data storage device, or subsequent to reading ofsome or all of the data from the data storage device. At step 177, datais read from the data storage medium. At step 178 at least a portion ofdata on the data storage medium is degraded. It is presumed that thedegraded data portion includes read-support information needed fordecoding data that is encoded, encrypted, or ordered in some manner.Step 178 may take place subsequent to, at the same time as, or at leastin part prior to reading of data from the data storage medium in step177. A data decoding step is performed at 179. At decision point 180,the quality of the data reading is assessed. If a good read of data hasbeen obtained, flow control moves to step 184, and the process ends. Ifa good read of data has not been obtained, flow control moves todecision point 181, and it is determined whether recovery ofread-support information is permitted. If recovery of read-supportinformation is not permitted, the read fails and the process ends. Ifhowever, recovery of read-support information is permitted, read-supportinformation may be recovered at step 182, and if information retrievalis determined to be satisfactory (at step 183) process control returnsto step 179, and data is decoded utilizing the retrieved read-supportinformation. Whether or not recovery of read-support information ispermitted may depend on the particular data storage device andsurrounding circumstances. For example, if the data storage devicecontains a movie to be viewed or a music recording that has expiredfollowing a certain number/duration of uses, permission to recoverread-support information (e.g., from a support entity) may be contingenton verification of payment of an additional rental/subscription fee. Ifthe data storage device contains confidential information, permission torecover read-support information after a limited use period has expiredmay be granted to a user who provides an appropriate security passwordor the like. These are only a few of many possible examples.

FIG. 8 is a schematic diagram illustrating exemplary systems andprocesses for reading data from a data storage device. A read devicecontaining system is indicated generally by reference number 1399, andmay be a system including hardware, firmware, and software. Anapplication program may transmit read request 1402 to operating system1404, which transmits read request 1410 to device driver 1408.Alternately, application program 1400 may send a read request 1406directly to device driver 1408. Device driver 1408 then submits readrequest 1412 to device interface 1414, which subsequently submits readrequest 1416 to data storage device reader 1418. Read requests may be inoptical, electrical, or other formats and generated and transmittedthrough the use of hardware, firmware, software, and combinationsthereof. In response to read request 1416, data storage device reader1418 may send a probe signal 1420 (e.g., an optical interrogationsignal) to data storage device 1422. Data storage device reader 1418then reads data from data storage device 1422. In some embodiments, datastorage device reader 1418 may transmit a degradation signal 1426 (whichcould be an electrical, magnetic, optical, or other signal) designed toproduce or initiate degradation of some or all of the data stored indata storage device 1422. Data signals 1424, 1426, 1428, and 1430 may betransmitted to data storage device reader 1418, device interface 1414,device driver 1408, and finally to application program 1400.Alternatively, a data signal 1432 may be transmitted from device driver1408 to operating system 1404 and then be transmitted to applicationprogram 1400 as data signal 1434. At some point between data storagedevice 1422 and the final recipient of the data (e.g. applicationprogram 1400 or operating system 1404), encoded data 1436 may be sent todata decoding module 1438, where it may be decoded with the use ofread-support information 1437. Prior to deactivation of data storagedevice 1422, read-support information 1437 may be read from data storagedevice 1422. Following deactivation of data storage device 1422,read-support information 1437 may not be obtainable from data storagedevice 1422. In such cases, a request 1442 may be sent to data recoverymodule 1444, which may include software, hardware, or firmwarecomponents of the data storage device reading system. Data recoverymodule 1444 may retrieve an override code as described previously, bysending a request 1446 to a user 1448, who then sends a request 1450 toa support entity 1452. In some embodiments, requests may be transmitteddirectly to support entity 1452 without user 1448 as intermediary. Inother embodiments, a request 1460 may be transmitted to special purposedata retrieval hardware/software 1462, that may be adapted to retrieveread-support information directly from a degraded or modified datastorage device. An override code 1454 may be transmitted to user 1448and then to data recovery module 1444 (at reference number 1456).Retrieved read-support information 1464 may be transmitted back to datarecovery module 1444. In other embodiments, suitable for cases where asecondary copy of read-support information is stored on data storagedevice 1422, a request 1466 may be sent from data recovery module 1444to a secondary key retrieval module 1468 configured to retrieve asecondary copy of read-support information from data storage device1422, where it may be stored in a secondary location. Data decodingoperations may be handled at the hardware or software level in readdevice containing system 1399. Recovered read-support information 1458is transmitted from data recovery module 1444 to data decoding module1438, where it may be used in reading or decoding of data.

Degrading or otherwise rendering inaccessible portions of data on a datastorage device may be performed by various methods, the choice of whichmay be based on the particular data storage device and read device used.In various embodiments described herein, data storage devices maycontain machine readable data. Machine readable data is commonly storedin a binary code, which may be stored in various data storage mediacapable of existing in at least two different states for binaryencoding. For example, data may be stored in patterns of electricalpotentials, magnetized regions, optically transmissive regions, oroptically reflective regions, among others, as known or as may bedevised by those of skill in the relevant arts. In some embodiments,data storage media capable of existing in more than two states may beused, and encoding schemes other than binary code may be used. Examplesof data storage media include optical and magnetic data storage media,as are well known for use in CDs or DVDs, and floppy disks and magnetictapes.

In some embodiments of data storage devices suitable for use in methodsand systems described herein, a data storage medium may be carried on asubstrate. The substrate may be a structure or layer that underlies orsupports the data storage medium, or a structure or layer that overliesor coats the data storage medium. The substrate may provide structuralstability or protect the data storage medium. In some embodiments, thesubstrate material may be interspersed with or formed integrally withthe data storage medium. As used herein, the term substrate refers to amaterial that does not itself store the data, but performs a structuralor protective function relative to the data storage medium. Data storedin the data storage medium may be read through the substrate in someembodiments of data storage devices, for example, by an interrogatinglight beam shining through a substrate layer of an optical disk to readdata from the disk. A degradation-sensitive region of a data storagedevice may include any portion of the data storage device that may bemodified in some way to render information stored in the regioninaccessible or unusable in some way. ‘Degradation’ may includemodification of data stored in a data storage medium, and/ormodification or damage to the substrate or data storage medium. In someembodiments a data storage device may include multiple layers or levelsin which data may be stored. Data stored at different levels may be readby a read system that focuses the interrogation signal (e.g., a lightbeam used in reading an optical data storage device) at the appropriatedepth or level within the data storage device. Depending on theconstruction of the data storage device and read system, data stored atdifferent levels may be accessed from a single side or from oppositesides of the data storage device.

FIGS. 9A-9H illustrate a number of exemplary forms of degradation ofdata. FIG. 9A depicts an exemplary portion of data stored in a binaryformat, as represented by data string 200. A first state of a datastorage medium may be represented by a ‘1’, while a second state may berepresented by a ‘0’ in data string 200. Degradation of data may includesetting all data values to a ‘0’, as represented by data string 202 inFIG. 9B, or setting all data values to a ‘1’, as represented by datastring 204 in FIG. 9C. Degradation of data may include resetting datavalues to random values or to some pattern (e.g., alternating ‘1’s and‘0’s) as represented by data string 206 in FIG. 9D. In each of theexamples shown in FIGS. 9B-9D, the data strings contain readable datavalues, but the data values are not ‘correct’, i.e., the read datavalues do not match the original data values. In other embodiments,following degradation, data may no longer be readable. As depicted inFIG. 9E, in some embodiments it may be the case that no data can be readat all, e.g., an attempt to read data string 208 produces a signal thatcannot be recognized as either a ‘1’ or a ‘0’. In other embodiments,partial data degradation may be obtained. Reduced signal-to-noise ratio,as shown in FIG. 9F may be considered a form of partial datadegradation; the data is present in data string 210 but accompanied by ahigher than usual level of noise. Partial degradation may also includethe case where a portion of machine readable data in the second dataportion is unreadable. FIG. 9G depicts an example in which data string212 is partially degraded. First data portion 214 and third data portion218 contain the original data values, but in second data portion 216,all data values have been set to ‘0’. FIG. 9H depicts another example ofpartial data degradation in data string 220. In FIG. 9H, first dataportion 222 and third data portion 226 contain original data values, butno data values can be read at all from second data portion 224.

FIGS. 9A-9H illustrate different forms of data degradation that may bemanifested in data read from a data storage device by a read device.FIGS. 10A-10D illustrate how different forms of data degradation may beobtained. FIG. 10A is a cross-sectional view of a portion of a datastorage device 250, including substrate 252, data storage medium 254,and digital data 256 stored in data storage medium 254. Data storagemedium 254 may be a material that can exist in two different states, oneof which is represented by the black rectangles, and the other of whichis represented by the shaded portion of data storage medium 254.Deactivation of a data storage device may include destruction ormodification of the data storage medium so that no data may be storedtherein, modification of data stored in a data storage medium,destruction or modification of a substrate or coating located adjacentor near a data storage medium considered to include destruction ormodification of data, as shown in various examples herein, or variousother modifications to the data storage device that in some way renderdata inaccessible. FIGS. 10B-10D illustrate possible modifications todata, data storage media, and substrate that may produce the differentforms of degradation illustrated in FIGS. 9B-9H.

In FIG. 10B, data storage medium 254 and stored data 256 are unmodified,but the substrate has been changed to a modified form 252′, whichprevents reading of stored data 256. For example, if data is readoptically, with the use of light transmitted through a transparentsubstrate, reading of data may be blocked, for example, by modifying ordegrading substrate 256 to block or hinder transmission of light throughthe substrate. Examples of such mechanisms are described, for example,in U.S. Pat. Nos. 6,839,316, 6,780,564, and 6,709,802, which areincorporated herein by reference. Modification of substrate 252′ maycompletely block reading of data, as depicted generally in FIG. 9E, ormay produce a reduced signal-to-noise ratio as depicted in FIG. 9F.Depending on the particular read system used, a modified substrate maylead to reading of data that are interpreted as all ‘0’s or all ‘1’s, asdepicted in FIGS. 9B and 9C, respectively.

In FIG. 10C, substrate 252 and data storage medium 254 are unmodified,but data stored in data storage medium 254 is changed to modified form256′, so that the data storage medium contains data values that differfrom the originally stored data 256 as shown in FIG. 10A are. Data maybe modified by writing or erasing of data, as is known in the art. Thedata modification represented in FIG. 10C could lead to complete orpartial data ‘degradation’, as depicted in FIG. 9B, 9C, 9D, or 9G.

FIG. 10D depicts a portion of data storage device 250 includingsubstrate 252, and data storage medium 254′, which has been modified sothat it is no longer capable of storing data. Data storage 254′ may bemodified or degraded in various ways, depending upon the type of datastorage medium. This may produce data degradation as depicted in FIG.9E, for example.

Machine readable data may be degradable by exposure to one of light,heat, moisture, chemicals, an electrical field, or a magnetic field, orit may be degradable by exposure to a combination of at least two oflight, heat, moisture, chemicals, mechanical damage, an electricalfield, or a magnetic field. In some embodiments, machine readable datamay be degradable in response to a single reading of the memory device,while in other embodiments, it may be degradable in response to betweenabout one and about 10 readings of the memory device. In still otherembodiments, machine readable data may be degradable by other numbers ofreadings of the memory device, and the numbers of readings specifiedherein are merely exemplary, rather than limiting. The machine readabledata may be stored in a data storage medium that includes at least oneof a magneto-optic material, a thermo-optic material, or anelectro-optic material. In some embodiments, machine readable data maybe stored in a data storage medium that includes at least one of aphotochromic dye, a photopolymer, or a photorefractive ferroelectricmaterial.

The substrate of the memory device may take various forms, for examplethe substrate may be a disk shaped substrate, a card, or microchip, forexample. In some embodiments, the substrate may include a rigidmaterial, while in others it may include a flexible material.

All or portions of data on a data storage device may be renderedinaccessible by degrading a subset of data on the data storage devicethat contains information necessary for reading data stored on otherparts of the data storage device. In embodiments as exemplified in FIGS.3 and 4, modification or destruction of portions of a data storagedevice containing index or key information may render data of intereststored in other portions of the data storage device inaccessible orunreadable. Degradation of the data storage medium may include one ormore of destruction of the data storage medium, modification of the datastorage medium, modification of data stored in the data storage medium,and modification of signal-to-noise ratio of data stored in the datastorage medium. Degradation may take place directly in response to adegradation inducing influence, or it may be initiated by a degradationinducing influence but continue to completion after removal of thedegradation inducing influence. This may be the case, for example, ifthe degradation inducing influence provides input of an activationenergy sufficient to overcome an energetic barrier and set off achemical process that proceeds without further input of energy onceinitiated. A degradation inducing influence may produce degradationdirectly, or may function as an intermediary to enable or initiateaction by a direct degradation inducing influence. Degradation mayinclude various combinations of two or more degradation mechanisms, andin some embodiments may be produced by synergistic or cooperativeeffects of two or more degradation inducing or producing factors orinfluences. Examples of modifiable features include, but are not limitedto, mechanical properties, optical properties, electrical properties,magnetic properties, or chemical properties.

Degradation of the substrate may include a change in a material propertyof the substrate or a change in shape or conformation of the substratematerial, such as thickness or surface texture. Material properties mayinclude optical properties such as reflectivity, index of refraction,transmissivity, light scattering, electrical properties, magneticproperties, and so forth. Modifications to material properties, shape,or conformation may be caused by a phase change, chemical reaction,melting, etching, corrosion, etc. of the substrate material due toexposure to a degradation inducing influence. Examples of degradationinducing influences or factors include, for example, heat, light, otherforms of electromagnetic radiation, pressure, a magnetic field, or anelectrical field. Degradation of data, data storage medium, or substratemay occur by a limited number of reads or uses or by a limited period oftime following initiation of degradation.

FIG. 11 depicts a data storage device 300 containing machine readabledata that may include a first data portion that is non-degradable by alimited number of readings, and a second data portion that is degradableby the limited number of readings, the second data portion comprisingread-support information necessary for reading data of interest from thefirst data portion, the memory device having associated therewith a copyor analog of the read-support information retained by a third party. Thefirst data portion contains stored data of interest 302 having a seconddata portion 304 containing read-support information 306. Read-supportinformation 306 may be index information, key information, or othertypes of information needed to support reading of data of interest 302.Region 304 containing read-support information 306 may be adegradation-sensitive region. The override code may include a full copyof the read-support information, as depicted in FIG. 11, which may beused to enable reading of data of interest 302 from first data portion300. Deactivation of the memory device may include degradation of thedegradation-sensitive region. For example, the degradation-sensitiveregion may be degraded by exposure to a degradation-inducing influenceto render the data of interest inaccessible to a user of the memorydevice. Data storage device 300 may also include device identificationcode 308. Device identification code 308 may be stored in a machinereadable format that can be read by a device used to read data from datastorage device 300. Alternatively, device identification code 308 may bein a machine readable format that is readable by a different reader, ofthe same or different type. For example, device identification code 308may be readable by an optical reader, a magnetic reader, or variousother readers. Device identification code 308 may be stored in anelectronic, magnetic or optical format, as found on magnetic or opticaldata storage media, or an optically readable format such as a bar code,for example. In some embodiments, a device identification code may be ahuman-readable code that may be read by a human user of the device, forexample an alphanumeric code printed or embossed on data storage device300 directly or on a label affixed to data storage device 300. FIG. 11also depicts a data storage location 310 that is distinct from datastorage device 300, in which is stored data storage deviceidentification code 312. Data storage device identification code 312contains the same information as data storage device identification code308. Data storage device identification code 312 may be stored in thesame or a different format than data storage device identification code308. For example, data storage device identification code 312 may bestored in an electronic, optical, or magnetic machine-readable format,or it may be stored in a human-readable format (for example, analphanumeric code printed on a sheet of paper). Override code 314 may bestored in data storage location 310 in association with data storagedevice identification code 312.

FIG. 12 depicts data storage device 300 following degradation of seconddata portion 304. Stored data of interest 302 is retained, butread-support information is fully degraded (degraded read-supportinformation is indicated by reference number 318). A backup copy ofread-support information 314 is stored in data storage location 310 andassociated with data storage device 300 by means of data storage deviceidentification code 312 stored in data storage location 310. Followingdeactivation (e.g., by degradation of second data portion 304), datastorage device 300 may be reactivated by retrieving read-supportinformation 314 from data storage location 310 according to a method asdepicted in FIGS. 8 and 9.

In some embodiments, as illustrated in FIG. 13, override code 322 mayinclude a portion of the read-support information from second dataportion 304. FIG. 13 depicts data storage device 300 as shown in FIG. 11following a degradation process that left partial read-supportinformation 320 in second data portion 304. Data storage location 310includes data storage device identification code 312 which matches datastorage device identification code 308 on data storage device 300, asbefore. Data storage location 310 includes override code 322 thatincludes a portion of read-support information. For example, the portionof the read-support information may supplement information that can beread from the data storage device to enable reading of data of interestfrom the data storage device. Alternatively, the original read-supportinformation may include redundancies such that an override code thatincludes only a portion of the read-support information may containsufficient information to enable reading of data of interest.

As illustrated in FIG. 14, in some embodiments data storage location 310may include override code 328 that includes an analog of the degradedread-support information 326, which may differ from the read-supportinformation that was originally stored in second data portion 304 on thedata storage device 300 in some aspect, but which is functionallyequivalent to the read-support information with respect to enablingreading of data of interest. The copy or analog of the read-supportinformation 328 may be associated with the memory device 300 through theuse of device identification codes 308 and 312. The copy or analog ofthe read-support information may be functionally analogous to theread-support information. In some embodiments, as depicted in FIG. 14,the analog may be functionally equivalent but different from theread-support information. In some embodiments, the copy or analog of theread-support information may include a full copy of the read-supportinformation, while in other embodiments the copy or analog of theread-support information may include a partial copy of the read-supportinformation.

As shown in FIGS. 15A and 15B and discussed previously in connectionwith FIG. 8, in some embodiments, a backup copy 408 of read-supportinformation 406 may be stored in a secondary location on the datastorage or memory device 400. FIG. 15A depicts data storage device 400prior to deactivation, in which data of interest is stored in region 402and read-support information 406 is stored in degradable second dataportion 404. Backup copy 408 of read-support information 406 is storedin a secondary location in data storage device 400, e.g., in region 402.Backup copy 408 may be read by special purpose software, discussed inconnection with FIG. 8. A method of reactivating the device may theninclude obtaining the backup copy 408 of the read-support information byreading the backup copy 408 from a secondary location on the memorydevice 400 as shown in FIG. 15B. The backup copy of the read-supportinformation may contain complete information necessary for reading thedata of interest, or it may be a subset of information necessary forreading the data of interest. In some cases, the backup copy may bestored in the secondary location of the memory device in encoded orencrypted form. For example, as shown in data storage device 450 in FIG.16, the backup copy 458 of read-support info 456 stored in location 454may be dispersed among the data of interest 452. Such dispersedread-support information may be distributed so that it can be retrievedonly with the use of special-purpose software (or firmware or hardware;operation performed by software can generally be performed in firmwareor hardware as well, and vice versa). Special purpose software mayinclude decoding or decryption software, lookup table software, or,certain signal-processing software.

As outlined in FIG. 17, a method of retrieving information from adeactivated memory device may include providing an identification codeto a support entity the identification code associated with adeactivated memory device that includes at least one region from whichread-support information sufficient to support reading of data ofinterest from the memory device could be read prior to deactivation butnot after deactivation at step 502 and receiving an override code fromthe support entity, the override code containing alternative informationsufficient to permit reading of the data of interest from thedeactivated memory device, at step 504.

FIG. 18 further elaborates on the method of retrieving information froma deactivated memory device outlined in FIG. 17. Step 552 includesproviding an identification code to a support entity, the identificationcode associated with a deactivated memory device that includes at leastone region from which read-support information sufficient to supportreading of data of interest from the memory device could be read priorto deactivation but not after deactivation. Three alternative methods ofproviding the identification code are depicted. Step 558 includesproviding the identification to the support entity via a telephone, step560 includes providing the identification code to the support entity viathe internet, and step 562 includes providing the identification code tothe support entity via a wireless transmission. Step 554 includesreceiving an override code from the support entity, the override codecontaining alternative information sufficient to permit reading of thedata of interest from the deactivated memory device.

In another embodiment of a method of retrieving information from adeactivated memory device, as shown in FIG. 19, at 602, anidentification code is provided to a support entity, the identificationcode associated with a deactivated memory device comprising at least oneregion from which read-support information sufficient to support readingof data of interest from the memory device could be read prior todeactivation but not after deactivation. At step 604, an override codeis received from the support entity, the override code containingalternative information sufficient to permit reading of the data ofinterest from the deactivated memory device. At step 606, thealternative information is used as a key to decode data of intereststored in the deactivated memory device.

FIG. 20 depicts a further variant in which at step 652, anidentification code is provided to a support entity, the identificationcode associated with a deactivated memory device comprising at least oneregion from which read-support information sufficient to support readingof data of interest from the memory device could be read prior todeactivation but not after deactivation. At step 654, an override codeis received from the support entity, the override code containingalternative information sufficient to permit reading of the data ofinterest from the deactivated memory device. At step 656, alternativeinformation is used as index information for reading data of intereststored in two or more locations of the deactivated memory device in acorrect sequence.

FIG. 21 depicts a further method of reactivating a deactivated memorydevice, which includes receiving an identification code associated witha deactivated memory device, the memory device including at least onedegraded degradation-sensitive region that prior to degradationpermitted access to machine readable information necessary for readingdata of interest from the memory device, as shown at step 702,identifying an override code associated with the identification code,wherein the override code contains read-support information necessary topermit data to be read from the deactivated memory device, as shown atstep 704, and providing the override code to a receiving entity at step706. Step 702, which includes receiving an identification codeassociated with a deactivated memory device may be performed by a numberof different methods, several of which are indicated in FIG. 21.Receiving an identification code may include receiving theidentification code from a user of the memory device at step 710.Alternatively, the method may include receiving the identification codefrom a representative of a user of the memory device at step 712. Forexample, if the method is performed at a repair shop, the user of thedevice may present the device and the identification code information toan employee of the repair shop, who may carry out the steps of thereactivation method. As a further alternative, the identification codemay be received in the form of an electronic data transmission as shownat 714, or in the form of a wireless data transmission, as shown at 716.The step of providing the override code to a receiving entity is alsosubject to variation: the method may include providing the override codeto a user of the memory device as indicated at 720, or a representativeof a user of the memory device as indicated at 722. The method mayinclude providing the override code in the form of an electronic datatransmission at step 724 or in the form of a wireless data transmissionat step 726. Electronic data transmissions may include data sent in theform of emails or attachments thereto, or various electronic datatransfer protocols as are known or may be developed by those of skill inthe art. The method of FIG. 21 may be performed in connection with adeactivated memory device in which the degradation-sensitive region hasbeen degraded by exposure to a degradation-inducing influence to renderthe data of interest inaccessible to the user. The override code mayinclude at least a portion of a decryption key or at least a portion ofan index table. The override code may include complete read-supportinformation sufficient for reading the data of interest from the memorydevice, or it may include partial read-support information necessary forreading the data of interest from the memory device. For example, thepartial read-support information in the override code may be sufficientfor reading the data of interest from the memory device when used incombination with partial read-support information stored on the memorydevice.

According to certain embodiments, as outlined in FIG. 22, a method ofretrieving data from an expired limited use memory device may includeobtaining a backup copy of read-support information necessary forreading machine readable data of interest from the expired limited usememory device, as shown at step 752, where the expired limited usememory device comprises a first portion containing the data of interestand a degraded degradation-sensitive second portion, and the backup copycomprises a copy of read-support information stored in the undegradeddegradation-sensitive second portion prior to expiration of the limiteduse memory. At step 754, based upon the read-support information, dataof interest may be read from the first portion of the expired limiteduse memory device.

FIG. 23 further details the method of FIG. 22, which includes obtaininga backup copy of read-support information necessary for reading machinereadable data of interest from the expired limited use memory device atstep 802, the expired limited use memory device comprising a firstportion containing the data of interest and a degradeddegradation-sensitive second portion, the backup copy comprising a copyof read-support information stored in the undegradeddegradation-sensitive second portion prior to expiration of the limiteduse memory. As shown at 808, the method further may include obtainingthe backup copy of the read-support information from a third party byproviding an identification code associated with the limited use memorydevice to the third party. The third party may be a support entity, forexample, that uses the identification code to determine the read-supportinformation that is obtained in step 802. At step 804, based upon theread-support information, data of interest may be read from the firstportion of the expired limited use memory device.

FIG. 24 further elaborates on the method of FIG. 23. A backup copy ofread-support information necessary for reading machine readable data ofinterest from the expired limited use memory device is obtained at step852. The expired limited use memory device comprises a first portioncontaining the data of interest and a degraded degradation-sensitivesecond portion, and the backup copy comprises a copy of read-supportinformation stored in the undegraded degradation-sensitive secondportion prior to expiration of the limited use memory. At step 854,based upon the read-support information, data of interest may be readfrom the first portion of the expired limited use memory device. Asshown at 858, the method may include obtaining the backup copy of theread-support information from a third party by providing anidentification code associated with the limited use memory device to thethird party. This may involve, for example, receiving the backup copy ofthe read-support information in an electronic format, as indicated at860. In some embodiments, obtaining the backup copy of the read-supportinformation may include receiving the backup copy of the read-supportinformation in a digital format, as indicated at 862. In otherembodiments, the method may include receiving the backup copy of theread-support information in the form of an alphanumeric code, asindicated at step 864, or a bar code, as indicated at step 866.

According to certain embodiments, as shown in FIG. 25, a method ofmanufacturing a limited use memory device may include providing asubstrate (step 902); providing a data storage medium on the substrate(step 904); forming a first data storage region on the substrate, thefirst data storage region including a substantially non-degradablematerial (step 906); forming a second data storage region on thesubstrate, the second data storage region including a degradablematerial (step 908); and storing a data storage device identificationcode associated with the data storage device in a data storage locationdistinct from the data storage device (step 910). The degradablematerial that is included in the second data storage region may includea degradable data storage medium, or it may include a degradable portionof the substrate.

The method depicted in FIG. 25 may be expanded as shown in FIG. 26.Steps 952-960 include providing a substrate (step 952); providing a datastorage medium on the substrate (step 954); forming a first data storageregion on the substrate, the first data storage region including asubstantially non-degradable material (step 956); forming a second datastorage region on the substrate, the second data storage regionincluding a degradable material (step 958); and storing a data storagedevice identification code associated with the data storage device in adata storage location distinct from the data storage device (step 960).The method illustrated in FIG. 26 also includes storing an override codeassociated with the data storage device in the data storage locationdistinct from the data storage device in association with the datastorage device identification code at step 962.

FIG. 27 depicts a further elaboration on the method of FIG. 25,including the steps of providing a substrate (step 1002); providing adata storage medium on the substrate (step 1004); forming a first datastorage region on the substrate, the first data storage region includinga substantially non-degradable material (step 1006); forming a seconddata storage region on the substrate, the second data storage regionincluding a degradable material (step 1008); and storing a data storagedevice identification code associated with the data storage device in adata storage location distinct from the data storage device (step 1010).The method may include storing a unique data storage deviceidentification code for one or more individual data storage devices(step 1014), or it may include storing a unique data storage deviceidentification code for one or more individual batches of data storagedevices (step 1016).

Storing a unique data storage device identification code for one or moreindividual data storage devices may be used when each data storagedevice has a unique identification code. Storing unique data storagedevice identification code for one or more individual batches of datastorage devices may be used in cases where data storage devices within abatch of data storage devices (e.g., a batch being all data storagedevices manufactured on one day, all data storage devices of aparticular type, or any other selected grouping of data storage devices)have the same device identification code, but data storage devices indifferent batches of data storage devices have different deviceidentification codes. Storing different data storage deviceidentification codes for individual batches as opposed to individualdevices may provide a lower level of security, but may be sufficient formany applications. FIG. 28 illustrates a first batch 1050 including datastorage devices 1054 a-1054 c and a second batch 1052 including datastorage devices 1056 a-1056 c. Each of data storage devices 1054 a-1054c includes data of interest 1058 a-1058 c, respectively, data storagedevice identification code 1062 a-1062 c, respectively, and read-supportinformation 1060 a-1060 c, respectively. Similarly, in second batch1052, each of data storage devices 1056 a-1056 c includes data ofinterest 1066 a-1066 c, respectively, data storage device identificationcode 1070 a-1070 c, respectively, and read-support information 1068a-1068 c, respectively. Data storage devices in first batch 1050 havedata storage device identification codes 1062 a-1062 c each with a valueof DSD0001, and corresponding read-support information 1060 a-1060 cwith a value of XXXXX. Data storage devices in second batch 1052 havedata storage device identification codes 1070 a-1070 c each with a valueof DSD0002, and corresponding read-support information 1068 a-1068 cwith a value of ZZZZZ. Data storage location 1072, which is a datastorage location distinct from the data storage devices (e.g., at aremote location, and/or retained by a third party) includes data storagedevice identification code 1074 having value DSD0001 associated withoverride code 1078, containing read-support information of value XXXXXfor reading data from data storage devices 1054 a-1054 c in first batch1050. Data storage location 1072 also includes data storage deviceidentification code 1076 having value DSD0002 associated with overridecode 1080, containing read-support information of value ZZZZZ forreading data from data storage devices 1056 a-1056 c in first batch1052.

FIG. 29 depicts a further variant of the method of FIG. 25, includingproviding a substrate (step 1152); providing a data storage medium onthe substrate (step 1154); forming a first data storage region on thesubstrate, the first data storage region including a substantiallynon-degradable material (step 1156); forming a second data storageregion on the substrate, the second data storage region including adegradable material (step 1158); and storing a data storage deviceidentification code associated with the data storage device in a datastorage location distinct from the data storage device (step 1160). Themethod includes the additional step of storing read-support informationin the second data storage region (step 1162). The method of FIG. 29 maybe performed, for example, in situations where the initial manufactureof the data storage device and storage of read-support information onthe data storage device are performed by the same party. In someprevious embodiments (e.g., as shown in FIG. 25) manufacture of the datastorage device may sometimes be performed by a different party thanstorage of read-support information and/or data on the data storagedevice.

FIG. 30 depicts a method including steps 1202-1212, which are the sameas step 1152-1162 in FIG. 29, with the additional step of storing a copyof the read-support information in the data storage location distinctfrom the data storage device, as indicated at 1214.

FIG. 31 depicts a further embodiment of a method of manufacturing a datastorage device which includes providing a substrate at 1252, providing adata storage medium on the substrate at 1254, forming a first datastorage region on the substrate at 1256, where the first data storageregion includes a substantially non-degradable material, and forming asecond data storage region on the substrate at 1258, where the seconddata storage region includes a degradable material, and storing a datastorage device identification code associated with the data storagedevice in a data storage location distinct from the data storage deviceat 1260. Substrates may take various forms and be constructed fromvarious materials. Providing a substrate may include providing a diskshaped substrate (as indicated at 1264) or a card shaped substrate (asindicated at 1266), for example. Providing a substrate may includeproviding a silicon-based substrate (as indicated at 1268), apolymer-based substrate (as indicated at 1270), or a ceramic-basedsubstrate (as indicated at 1272), for example. Providing a data storagemedium may include providing at least one of a magneto-optic material, athermo-optic material, or an electro-optic material (as indicated at1274). Providing a data storage medium may include providing at leastone of a photochromic dye, a photopolymer, or a photorefractiveferroelectric material (as indicated at 1276).

As shown in FIG. 32, a method of configuring a limited use memory devicemay include storing a first data portion including data of interest in afirst data storage region of a limited use memory device (step 1302),the first data storage region including a relatively non-degradablematerial; storing a second data portion including read-supportinformation necessary for reading the data of interest from the firstdata storage region in a second data storage region of the limited usememory device (step 1304), the second data storage region including arelatively degradable material; and saving an identification codeassociated with the limited use memory device in a data storage locationdistinct from the limited use memory device (step 1306).

FIG. 33 illustrates a further expansion on the method shown in FIG. 32.As in FIG. 32, the method may include storing a first data portionincluding data of interest in a first data storage region of a limiteduse memory device (step 1352), the first data storage region including arelatively non-degradable material; storing a second data portionincluding read-support information necessary for reading the data ofinterest from the first data storage region in a second data storageregion of the limited use memory device (step 1354), the second datastorage region including a relatively degradable material; and saving anidentification code associated with the limited use memory device in adata storage location distinct from the limited use memory device (step1356). The method further may include saving an override code associatedwith the limited use memory device in association with theidentification code in a data storage location distinct from the limiteduse memory device, the override code containing information necessary toread data of interest from the first data portion following degradationof read-support information stored in the second data storage region(step 1358). Saving the override code may be performed in severaldifferent ways, including storing a copy of the read-support informationstored in the second data storage region (step 1362), storing a copy ofa portion of the read-support information stored in the second datastorage region (step 1364), or saving information different from theread-support information stored in the second data storage region (step1366).

Read-support information may be stored in various different ways anddifferent formats, so that access to the read-support information may becontingent upon access to a read device including appropriate hardwareand/or software following degradation or inactivation of the datastorage device. For example, read-support information may be partiallymodified or degraded, so that it is readable only by special hardware orsoftware. Alternatively, it may be undegraded, but hidden by encryptionor by being stored in a form that is readable only by special-purposesystem, e.g. because it is stored in a different medium (as theinitially readable data), or stored in the same medium at a differentspatial frequency, position, or depth with the medium.

According to various embodiments as describe herein, methods ofobtaining read-support information in order to retrieve data of interestfrom, or ‘reactivate’, a deactivated memory device may be performedcompletely under microprocessor control. In other embodiments, retrievalof information from a deactivated memory device may be performed withcertain intermediate steps performed with human intervention orinvolvement. Various method steps as described herein may be performedby hardware, software, firmware, or combinations thereof, as is wellknown to those of skill in the arts of hardware and software design.

Although discussion herein focuses on ‘reactivation’ of data storagedevices that have been deactivated by the degradation (or othermodification) of read-support information, which blocks access to datastored in a portion of a data storage device, in other embodiments theblocking and unblocking effect obtained by degradation and subsequentretrieval of read-support information may be used to activate ordeactivate selected portions of the data storage device, so that (forexample) different data may be read from the data storage device on thefirst reading than on the subsequent readings. It will be appreciatedthat the general approach described herein for obtaining a backup copyof read-support information may similarly be applied to blockinginformation, in order to activate or deactivate ‘blocking’ of reading,or to activate or deactivate selected portions of a data storage device.In some cases, read-support information may be more appropriately termedread-control information in that its presence/accessibility orabsence/inaccessibility may determine which of two (or possibly more)portions of data on a data storage medium will be accessed or executed.For example, read control information may switch between apassword-protected version of data of interest, and anon-password-protected version of data of interest. This is but one ofmany possible applications of this general approach.

Referring back to FIG. 8, one general approach for retrieving data froman expired memory device or data storage device may including usingspecial purpose hardware of software (at 1462) to retrieve read-supportinformation from the data storage data, the read-support informationbeing inaccessible to the system previously used to read theread-support information. In other words, some or all of the datastorage device may have differing levels of readability to differingdata read systems. It is presumed that a first type of read system maybe routinely used by the use of the data storage device, and a secondtype of read system having different read capabilities may be used torecover data from an expired data storage device. Different readcapabilities may be conferred by special hardware (that may beavailable, for example, at a service shop) or special software (that maybe available at a service shop, or be accessed, downloaded, or otherwiseobtained by the user for installation on the normally used system, forexample, by paying a fee, entering a password, or meeting some otherrequirement for gaining access to the special purpose software). FIG.34A illustrates in schematic form the use of a first type of read system1400 for reading stored data from an unmodified data storage device1402. Successfully read data is indicated at 1404. FIG. 34B illustratesin schematic form the attempted use of a first type of read system 1400for reading stored data from a degraded or deactivated data storagedevice 1402′. A successful data read is not obtained. FIG. 34Cillustrates the use of a second type of read system 1406 for readingstored data from degraded or deactivated data storage device 1402′.Successfully read data is indicated at 1404.

According to one exemplary embodiment, a memory device may include asubstrate, a data storage medium on the substrate, and machine readabledata stored in the data storage medium. The machine readable data mayhave a first readability, and the readability of at least a portion ofthe machine readable data may be modifiable by a limited expectedlifetime so that following modification of readability, the modifiedportion of machine readable data may have a second readability. Datahaving the first readability may be readable by a first type of dataread system, while data having the second readability is not readable bythe first type of data read system. In some cases, data having thesecond readability may be readable by a second type of data read system,while in other cases, data having the second readability may besubstantially unreadable.

In the above exemplary embodiment, the limited expected lifetime may bedefined by a limited number of readings of the machine readable datafrom the memory device, or a limited number of uses of the memory device(not limited to reading, but including other uses or treatment of thememory device as well). Alternatively, the limited expected lifetime maybe defined by a limited time interval following an initial use of thedevice.

Machine readable data having the second readability may have a reducedsignal-to-noise ratio, an increased bit error rate, or reducedredundancy relative to machine readable data having the firstreadability.

In a further related embodiment, the readability of at least one firstportion of the machine readable data may be modifiable by the limitedexpected lifetime while readability of at least one second portion ofthe machine readable data may not be modifiable by the limited expectedlifetime, and the at least one first portion may contain read-supportinformation needed for reading data of interest in the at least onesecond portion. The read-support information may include a decryptionkey or index information. The machine readable data in the at least onefirst portion having the second readability may have a reducedsignal-to-noise ratio, increased bit error rate, or reduced redundancyrelative to machine readable data having the first readability.

In still another related embodiment of a memory device 1450, as depictedin FIG. 35, a first portion of data may include read control information1452 and second data portion 1454 and third portion data 1456 includedata of interest. Modification of the read control information maycontrol whether data of interest is read from the second data portion1454 or third data portion 1456. Readability of at least one firstportion of the machine readable data may be modifiable by the limitedexpected lifetime, while readability of at least one second portion andat least one third portion of the machine readable data may not bemodifiable by the limited expected lifetime. The at least one firstportion may contain read-control information, which for example maycause data to be read from the at least one second portion when the atleast one first portion has the first readability, and cause data to beread from the at least one third portion when the at least one firstportion has the second readability.

FIG. 36 depicts an exemplary data storage device 1500 including a firstportion 1502 and second portion 1504. The machine readable data in theat least one first portion 1502 having the second readability may besubstantially unreadable, in which case additional read-supportinformation 1506 may be stored in the at least one second portion 1504and retrievable with a special purpose read system. For example, if thedata storage medium is an optical data storage medium, the additionalread-support information may be readable at a different opticalwavelength than is the data of interest, or the memory device mayinclude a magnetic data storage medium in which the additionalread-support information is stored. Conversely, data of interest may bestored in a magnetic data storage medium and additional read-supportinformation stored in an optical data storage medium. Other alternativedata storage media in which additional read-support information can bestored include one or more resonant circuits or RFIDs. Additionalread-support information may be stored in a bar code on the memorydevice (which may be read optically, for example, but on a differentscale than the data of interest that may be stored in optical form inthe memory device. Additional read-support information may be stored inthe same type of data storage medium as the data of interest, but in adifferent format: for example, the additional read-support informationmay be stored at a different spatial frequency. FIG. 37 depicts incross-sectional view a data storage device 1550 including a substrate1554 and data storage medium 1552 including data 1556 stored at a firstspatial frequency and data 1558 stored at a second spatial frequency.

Additional read-support information may be retrievable by a specialpurpose read system including one or both of special purpose software orspecial purpose hardware.

Additional read-support information may be stored in various formats,and may include full, partial, or alternative versions of theread-support information in the first portion. The additionalread-support information may include at least one copy of theread-support in the at least one first portion or a portion of theread-support in the at least one first portion. The portion of theread-support information may be complementary to a residual portion ofthe read-support information readable from the at least one firstportion following modification of readability, as illustrated in FIG.13. In some embodiments, the additional read-support information may bedistributed among multiple locations in the at least one second portion,as illustrated in FIG. 16. Additional read-support informationdistributed among the multiple locations may be retrievable with the useof index information. In some embodiments, additional read-supportinformation may be stored in the at least one second portion inencrypted form. For example, additional read-support information may beencrypted by a public key encryption method such as a Diff-Hellman, RSA,EIGami, DSS, Elliptic curve, Paillier cryptosystem, orPassword-authenticated Key agreement encryption method or a private keyencryption method such as DES (see, e.g., Donald E. Knuth, The Art ofComputer Programming, Volume 1: Fundamental Algorithms, Third Edition,Reading, Mass., Addison-Wesley, 1997; Volume 2: SeminumericalAlgorithms, Third Edition, Reading, Mass., Addison-Wesley, 1998).

Readability of the machine readable data may be modifiable throughdegradation of the data storage medium, which may include material thatis degradable by exposure to one of light, heat, moisture, chemicals, anelectrical field, or a magnetic field. Alternatively, readability of themachine readable data may be modifiable through degradation of thesubstrate, which may be, for example, a material that is degradable byexposure to one of light, heat, moisture, chemicals, an electricalfield, or a magnetic field. In some embodiments, readability of themachine readable data may be modifiable through erasure or writing overof at least a portion of the machine readable data.

Another exemplary embodiment of a memory device may include a datastorage medium and machine readable data stored in the data storagemedium, with at least one first portion of the machine readable datahaving a limited expected lifetime after an initial read of data, duringwhich the machine readable data can be read from the data storage mediumby a first type of data read system, and following which the readabilityof the at least one first portion of the machine readable data ismodified so that it is unreadable by the first type of data read system.The limited expected lifetime of the memory device may be imposed bydegradation of at least a portion of the memory device by exposure toone or more of light, heat, moisture, chemicals, an electrical field, ora magnetic field.

In some embodiments, the at least one first portion of the machinereadable data may be substantially unreadable following the limitedexpected lifetime. However, in various exemplary embodiments, the atleast one first portion of the machine readable data is readable by asecond type of data read system following the limited expected lifetime.The second type of data read system may differ from the first type ofdata read system in some manner. For example, during the limitedexpected lifetime, the at least one first portion of the machinereadable data may be readable by an optical data read system. Followingthe limited expected lifetime, the at least one first portion of themachine readable data may be readable by an optical data read systemoperating at a reduced scan speed relative to a general purpose opticaldata read system. Or, following the limited expected lifetime, the atleast one first portion of the machine readable data may be readable byan optical data read system performing signal averaging on the datasignal. Alternatively, during the limited expected lifetime, the atleast one first portion of the machine readable data may be readable bya magnetic data read system, while following the limited expectedlifetime, the at least one first portion of the machine readable datamay be readable by a magnetic data read system operating at a reducedscan speed relative to a general purpose magnetic data read system. As afurther alternative, following the limited expected lifetime, the atleast one first portion of the machine readable data is readable by amagnetic data read system performing signal averaging on the datasignal.

The at least one first portion of the machine readable data may containread-support information necessary for reading data of interest in atleast one second portion of machine readable data, such as all or aportion of a decryption key (e.g., a private key or a public key).Read-support information may include locational information relating tothe location of the data of interest within the at least one secondportion of machine readable data.

In some embodiments, the at least one second portion may includeadditional read-support information needed for reading data of interestin the at least one second portion. One or more copies of theread-support information may be stored on the memory device. At leastone of the one or more copies of the read-support information may bestored in encrypted form. At least one of the one or more copies may beretrievable from the at least one first portion through the use ofspecial purpose software. By way of example, such special purposesoftware may include a function such as a HASH function, a table lookupfunction, or a decryption algorithm. At least one of the one or morecopies may be retrievable from the at least one first portion throughthe use of special purpose hardware. In one alternative embodiment, acopy or analog of the read-support information may be retained by athird party, instead of or in addition to being stored on the memorydevice.

In another exemplary embodiment, a data storage device may include:

A data storage medium capable of having machine readable data storedtherein, the data storage medium capable of producing a data signal in adata read device in response to an interrogation activity by the dataread device, the data storage medium including:

at least one modifiable portion capable of producing a data signalwithin a first signal range at the start of a limited read periodcharacterized by a limited expected lifetime or limited temporalduration, and modifiable to produce a read signal failing within asecond signal range subsequent to the limited read period.

In the above embodiment, a data signal within the first signal range maybe readable by a general purpose read device and a data signal withinthe second signal range may be readable by a special purpose read devicebut not by a general purpose read device. For example, a data signalwithin the first signal range may be characterized by a firstsignal-to-noise ratio and a data signal within the second signal rangemay be characterized by a second signal-to-noise ratio. As a secondexample, data signals within the first signal range may be characterizedby a first bit data error rate and a data signal within the secondsignal range may be characterized by a second bit data error rate. Thedata storage device may include a data storage medium capable ofproducing a data signal in an optical data read device, or a datastorage medium capable of producing a data signal in a magnetic dataread device, but is not limited to any specific types of data storagemedia.

As shown in FIG. 38, an exemplary method for manufacturing memorydevices as described herein may include providing a substrate at step1602, providing a primary data storage medium on the substrate at step1604, and storing machine readable data in the primary data storagemedium at step 1606. The machine readable data may initially be readableby a first type of data read system; at least a portion of at least oneof the substrate and the primary data storage medium may be modifiableby a limited expected lifetime to render at least a portion of themachine readable data unreadable by the first type of data read system.According to the method, the at least a portion of at least one of thesubstrate and the primary data storage medium may be modifiable by alimited expected lifetime to render at least a portion of the machinereadable data unreadable by the first type of data read system butreadable by a second type of data read system. As noted herein, thelimited expected lifetime may be defined by a limited number of readingsof the machine readable data from the memory device, by a limited numberof uses of the memory device, or by a limited time interval following aninitial use of the device. The method may include providing a substratehaving at least one degradable portion, wherein the at least onedegradable portion is degradable by the limited expected lifetime torender the at least a portion of the machine readable data unreadable bythe first type of data read system but readable by the second type ofdata read system. Alternatively, or in addition, the method may includeproviding a degradable primary data storage medium on at least a portionof the substrate, wherein the degradable primary data storage medium ismodifiable by the limited expected lifetime to render the at least aportion of the machine readable data unreadable by the first type ofdata read system but readable by the second type of data read system.The degradable primary data storage medium may include a photosensitivematerial, an electromagnetically-sensitive material, athermally-sensitive material, a moisture-sensitive material, or achemical-sensitive material.

In some variants of the above embodiment, prior to the limited expectedlifetime the portion of machine readable data may be readable by a firsttype of data read system selected from an optical data read system and amagnetic data read system.

A number of approaches may be used to provide machine readable data thatis modifiable by a limited expected lifetime and has differentreadability before and after the limited expected lifetime. Depending onhow the data is modified over the limited expected lifetime, differentmethods of providing data may be effective. In some embodiments, themethod may include storing machine readable data including multiplecopies of data of interest. In some embodiments, the method may includestoring machine readable data including redundancies within the data ofinterest, wherein the machine readable data is modifiable by the limitedexpected lifetime so that the redundancy in the data of interest isreduced. Following the limited expected lifetime the signal-to-noiseratio of the data of interest may be reduced relative to thesignal-to-noise ratio prior to the limited expected lifetime. Theportion of machine readable data may then be readable by a second typeof data read system that performs signal averaging of multiple reads ofthe portion of machine readable data. Alternatively, or in addition,following the limited expected lifetime the portion of machine readabledata may be readable by a second type of data read system thatdetermines a moving average of the machine readable data. As a furtheralternative, following the limited expected lifetime the portion ofmachine readable data may be readable by a second type of data readsystem that reads data from the at a reduced scan rate relative to ascan rate used by the first type of data read system.

In one variation, the method may include storing at least one firstportion of machine readable data in at least one first portion of theprimary data storage medium and storing at least one second portion ofmachine readable data in at least one second portion of the primary datastorage medium, the at least one first portion of machine readable datamodifiable by a limited expected lifetime to render the at least onefirst portion of machine readable data unreadable by the first type ofdata read system but readable by the second type of data read system,and the at least one second portion of machine readable datasubstantially unmodifiable by the limited expected lifetime. The methodmay also include storing read-support information in the at least onefirst portion of the primary data storage medium and storing data ofinterest in the at least one second portion of the primary data storagemedium, the read-support information necessary for reading the data ofinterest from the at least one second portion of the primary datastorage medium. As illustrated by the data storage device 1650 shown inFIG. 39, the method may include storing two or more copies of theread-support information (1656, 1658, 1660) in the at least one firstportion 1652 of the primary data storage medium. Data of interest isindicated at 1654. The multiple copies of read-support information(1656, 1658, 1660) may be averaged to obtain averaged read-supportinformation 1662. As illustrated by data storage device 1700 depicted inFIG. 40, the stored read-support information 1702 may include redundantinformation 1706, relative to the necessary read-support information1708, and the stored read-support information may be modifiable byreduction in redundancy by the limited expected lifetime. FIG. 41depicts data storage device 1700 following degradation. Degradedread-support information 1702′ has diminished redundancy in storedinformation 1706′, but the necessary read-support information 1708 isstill contained therein.

The method may include storing secondary read-support information on thememory device, the secondary read-support information being readablewith the second type of data read system but not the first type of dataread system. The method may additionally include storing secondaryread-support information in the at least one second portion of theprimary data storage medium distributed in the data of interest. Forexample, this may include storing the secondary read-support informationin the at least one second portion of the primary data storage medium ina different format than the data of interest, or storing secondaryread-support information in the at least one second portion of theprimary data storage medium in encrypted form. Public key or private keyencryption methods may be used, for example.

Another approach for storing secondary read-support information is tostore secondary read-support information in a secondary data storagemedium that may be different than the primary data storage medium.Exemplary secondary data storage media include one or more RFIDs orresonant circuits, optical data storage media (used with a magneticprimary data storage media) or magnetic data storage media (used with anoptical primary data storage media).

In yet another approach, as shown in FIG. 42 the primary data storagemedium 1756 (shown on substrate 1752 of data storage device 1750,illustrated here in cross-section) may be an optical data storagemedium, and the method may include storing secondary read-supportinformation 1756 in the at least one second portion of the primary datastorage medium at a different levels in the primary data storage mediumthan the data of interest 1754. The approach may be used in optical datastorage device capable of storing data in multiple layers or levels ofthe device; such device may include from two to as many as five or morelayers.

In another approach, which may be used with magnetic or optical datastorage media, among others, the method may include storing secondaryread-support information in the at least one second portion of theprimary data storage medium at a different spatial frequency in theprimary data storage medium than the data of interest.

In optical media, secondary read-support information may be stored inthe at least one second portion of the primary data storage medium thatis readable by a different optical wavelength than the data of interest.

FIG. 43 depicts another exemplary method of manufacturing a data storagedevice, which may include:

storing primary read-support information in a first data storage regionof the data storage device, the first data storage region having anexpected lifetime limit during which the primary read-supportinformation can be read from the first data storage region with a firsttype of data read system (step 1802);

storing secondary, read-support information in a second data storageregion of the data storage device, the secondary read-supportinformation readable from the second data storage region with a secondtype of data read system but not with the first type of data read system(step 1804); and

storing data of interest in the second data storage region, the data ofinterest readable with support of the primary read-support informationby the first type of data read system and readable with support of thesecondary read-support information by the second type of data readsystem (step 1806).

Secondary read-support information may be stored in the second datastorage region in encrypted form. The primary read-support informationmay include a decryption key, which may be, for example, a private keyor a public key. Alternatively, the primary read-support informationincludes index information used for determining locations from which toread data of interest from the data storage device in correct sequence.The method may include storing the primary read-support information in adegradable first data storage region, wherein the expected lifetimelimit during which primary read-support information can be read from thefirst data storage region with the first type of data read system isdetermined by the degradation of the degradable first data storageregion. The degradable first data storage region is degradable, forexample, by exposure to at least one of light, heat, oxygen, moisture, achemical, or an electromagnetic field.

An exemplary method of configuring a memory device, as shown in FIG. 44,may include:

providing a memory device including a first data storage regionincluding a material that is modifiable by a limited expected lifetimeof data from the data storage region and a second data storage regionincluding a material that is substantially unmodifiable by a limitednumber of reading of data from the data storage region (step 152);

storing primary read-support information in the first data storageregion that is readable prior to modification of the material by a firstdata read system (step 1854);

storing data of interest that is readable with use of the read-supportinformation in the second data storage region (step 1856); and

providing read-support information on the memory device that is readableby a second data read system but not the first data read system (step1858).

The method of configuring a memory device may include providingread-support information on the memory device that is readable by asecond data read system but not the first data read system by storingread-support information in the first data storage region in a formatthat is readable by the first data read system prior to modification ofthe material and is readable by the second data read system but not thefirst data read system subsequent to modification of the material. Aformat readable by the first data read system may include redundancy,and following modification the level of redundancy may be reduced to alevel readable by the second data read system but not the first dataread system. In some embodiments, the format readable by the first dataread system may include multiple copies of the read-support informationof which only one is read by the first data read system, and whereinfollowing modification the signal-to-noise ratio of the copies isreduced so to a level that is unreadable by the first data read systembut readable by the second data read system by averaging of the multiplecopies.

Providing read-support information on the memory device that is readableby a second data read system but not the first data read system may beaccomplished by storing secondary read-support information in the seconddata storage region. Secondary read-support information may be stored atone or more locations in the second data storage region, whereininformation about the one or more locations is available to the seconddata read system but not the first data read system.

In some embodiments, primary read-support information may include indexinformation or an encryption key such as a private key or a public key.

In some embodiments, data of interest may be stored in an optical datastorage medium, or a magnetic data storage medium, among others.Read-support information may be provided that is readable by an opticaldata read device or a magnetic data read device. Secondary read-supportinformation may be provided on the memory device in the form of at leastone RFID or resonant circuit.

Data stored on expired limited use memory devices according to methodsas described herein may be retrieved with suitably constructed datarecovery methods and systems. As shown in FIG. 45, one exemplary methodof retrieving data from an expired limited use memory device may includerecovering read-support information necessary for reading machinereadable data of interest from the expired limited use memory deviceusing a special-purpose data read system, the expired limited use memorydevice including a degraded first portion from which read-supportinformation could be read prior to expiration of the memory device witha general-purpose data read system, and at least one second portioncontaining the data of interest, as shown at step 1902, and reading dataof interest from the at least one second portion of the expired limiteduse memory device through the use of the read-support information, asshown at step 1904. In some applications, the method may includerecovering read-support information from the degraded first portion ofthe limited use memory device. The method may include recoveringread-support information from the degraded first portion of the limiteduse memory device using a data read system operating at a reducedscanning speed relative to a general-purpose data read system, or it mayinclude recovering read-support information from the degraded firstportion of the limited use memory device using a data read system thatperforms signal averaging on the read data. In some embodiments, thedata read system may perform a moving average on the read data.

In cases where the degraded first data portion includes two or moredegraded copies of the read-support information, the data read systemmay average the two or more degraded copies of the read-supportinformation, as depicted herein in FIG. 39. This may improve thesignal-to-noise ratio, for example. In cases where read-supportinformation is distributed among the data of interest in the at leastone second portion of the limited use memory device, the read-supportinformation may be recovered using a special-purpose data read systemincluding extraction software. The extraction software may include atleast one function, such as a HASH function or a decryption function, orit may include a lookup table operation.

Recovered read-support information may include complete informationnecessary for reading the data of interest, or a subset of informationnecessary for reading the data of interest. In some embodiments, themethod may include recovering partial read-support information from thedegraded first portion of the limited use memory device and recoveringcomplimentary partial read-support information from the at least onesecond portion of the limited use memory device, wherein the partialread-support information and complementary read-support informationtogether are sufficient to support reading of the data of interest fromthe at least one second portion of the limited use memory device, asillustrated in FIG. 13.

As shown in FIG. 46, a further exemplary method of retrieving data froman expired limited use memory device may include reading read-supportinformation from an expired limited use memory device with a specialpurpose read system, the read-support information of the expired limiteduse memory device readable by a special purpose read system but not ageneral purpose read system, as shown at step 1952; and reading data ofinterest from the expired limited use memory device with the use of theread-support information, as shown at step 1954. If the read-supportinformation includes a decryption key, the method may also includedecrypting the data of interest, while if the read-support informationincludes index information, the method may include locating andsequencing the data of interest.

The method may include reading the read-support information from theexpired limited use memory device with the use of a noise reductiontechnique, which may include, for example, a thresholding operation,performing a moving average, or performing signal averaging. In someembodiments, reading the read-support information from the expiredlimited use memory device may include using an error detection techniqueincluding an error detection code. The method may include reading theread-support information from the expired limited use memory deviceincludes using an error correction code. One or both of error detectionor error correction may be formed, though error correction is commonlyperformed in connection with error detection.

In a further alternative embodiment, depicted in FIG. 47, a method ofretrieving data from an expired limited use memory device may includereading at least one first portion of machine readable data from anexpired limited use memory device with a high-sensitivity read device,the at least one first portion having a decreased signal-to-noise ratiorelative to the signal-to-noise ratio of the at least one first portionprior to expiration the limited use memory device (step 2002). Themethod may include reading at least one first portion of machinereadable data from an expired limited use memory device with ahigh-sensitivity read device that performs signal averaging on the atleast one first portion. In some embodiments the high-sensitivity readdevice may perform a thresholding operation on the at least one firstportion. The high-sensitivity read device may include normal-sensitivityread-device hardware configured with special purpose software orfirmware. Alternatively, the high-sensitivity read device may includespecial purpose hardware components.

In some embodiments, the method may include using information containedin the at least one first portion of machine readable data to enablereading of data from at least one second portion of machine readabledata on the expired limited use memory device. The at least one secondportion of machine readable data on the expired limited use memorydevice may have a signal-to-noise ratio substantially the same as thesignal-to-noise ratio of the at least one first portion prior toexpiration of the limited use memory device.

In one exemplary embodiment, a system for recovering data from expireddata storage devices may include a data recovery device including areceptacle adapted to receive a data storage device, a read headpositionable within the receptacle to read data from an expired datastorage device received within the receptacle, a first sensor located onthe read head for sensing data from the data storage device, and acontroller configured to control at least one of the position of theread head position, operation of the first sensor, or processing ofsensed data to recover data from at least a portion of an expired datastorage device. The controller may include drive controller hardwareand/or software, software resident in a computer or other systemincluding a read device (as depicted generally in FIGS. 1 and 2). Thecontroller may include hardware, software, firmware, or combinationsthereof, and may be resident in a single device or distributed betweentwo or more devices or components. The controller may be configured tocontrol the position of the read head to locate the read head over atleast one degraded data portion of an expired data storage device. Insome embodiments, the controller may be configured to scan the read headover the degraded data portion at a reduced scan speed relative to thescan speed of a general purpose read device, wherein data in thedegraded data portion is readable at the reduced scan speed but not atthe scan speed of a general purpose read device. The data recoverydevice may include a controller configured to perform a moving averageon data read from the degraded data portion, the degraded data portionhaving a reduced signal-to-noise ratio relative to the signal-to-noiseratio of the data portion prior to degradation, to produce an improvedsignal-to-noise ratio in the data signal. Alternatively, or in addition,the controller may be configured to use an error-detection code todetect one or more errors from data read from the degraded data portion,the degraded data portion have an increased bit error rate relative tothe bit error rate of the data portion prior to degradation. Thecontroller may be configured to use an error-correction code to correctdetected errors in data read from the degraded data portion. A number oferror detection and correction codes are known to those of skill in theart, including but not limited to, parity functions, cyclic redundancychecks, Hamming codes, Reed-Solomon codes, and so on.

The controller may be configured to control read head position to locatea read head over two or more degraded data portions of an expired datastorage device and to average two or more degraded data sets read fromthe two or more data portions to produce a data set having an improvedsignal-to-noise ratio. In some embodiments, the controller may beconfigured to control read head position to locate a read head over anon-degraded portion of an expired data storage device that includes anon-degraded portion including data of interest and a degraded portionthat prior to expiration included read-support information necessary forreading the data of interest and to recover read-support informationfrom one or more locations within the non-degraded portion, wherein theread-support information is located at the one or more locationsinterspersed with the data of interest. The controller may be configuredto control read head position to position the read head over anon-degraded portion of an expired data storage device that includesread-support information necessary for reading the data of interestencoded at a different spatial frequency than the data of interest andto read the read-support information from the non-degraded portion ofthe expired data storage device, or to position the read head over anon-degraded portion of an expired data storage device that includesread-support information necessary for reading the data of intereststored at a different level than the data of interest and to read theread-support information from the non-degraded portion of the expireddata storage device.

The first sensor may be an optical sensor adapted to sense an opticalsignal from an optical data storage device, for example. The datarecovery device may also include a second sensor adapted to senseinformation from an optical data storage medium at a different opticalwavelength than the wavelength used by the first sensor, or at adifferent depth level of the expired data storage device than is read bythe first sensor. A read device 2050 including two different sensors2052 and 2054 of different types on read head 86 is depicted in FIG. 48.Other components (74-84) may be as depicted and described previously inFIG. 2. In some embodiments, the second sensor may be adapted to senseinformation from a different side of an optical data storage medium thanis sensed by the first sensor. Alternatively, the first sensor is amagnetic sensor may be adapted to sense a magnetic signal from amagnetic data storage device. The second sensor may be adapted to readinformation from a different type of data storage medium than said firstsensor. In some embodiments, the second sensor may be an optical sensoror a magnetic sensor. In some embodiments, the second sensor may beadapted to read information from at least one RFID or resonant circuiton the expired data storage device.

In another exemplary embodiment, a data recovery system may include aread head, a sensor, drive control hardware, and drive control software,where at least one of the drive control hardware and drive controlsoftware is configured to recover read-support information from anexpired data storage device and to read data of interest from theinformation. The read head may be an optical read head, a magnetic readhead, or some other type of read head. The system may include decodinghardware or software configured to decode encoded read-supportinformation recovered from an expired data storage device. For example,the decoding hardware or software may include a function such as a HASHfunction or a decryption function (e.g., public key decryption functionor a symmetric key decryption function), or a table-lookup operation fordecoding read-support information stored in multiple locations on theexpired data storage device, said multiple locations stored in a lookuptable used by the table-lookup operation.

The data recovery system may include drive control hardware, which maybe configured to read read-support information from an expired datastorage device at a reduced read speed or to control the level of thedata storage device from which read-support information is read. Forexample, in some embodiments, drive control hardware may be configuredto control reading of read-support information from a first level of anexpired data storage device and to control reading of data of interestfrom a second level of an expired data storage device. Drive controlhardware may be configured to adjust the spatial frequency at whichread-support information is read from the expired data storage device.

In some embodiments, the data recovery system may include signalprocessing software configured to perform signal averaging of multiplecopies of low signal-to-noise ratio read-support information read froman expired data storage device.

At least one of the drive control hardware and drive control softwaremay be configured to recover secondary read-support informationdistributed in the data of interest.

A computer program that may be used in connection with systems asdescribed herein may include, for example, instructions for performingan interrogation activity with a data read device, instructions fordetecting a read response from a data storage device in response to theinterrogation activity with the data read device, and instructions forcomparing a detected read response with an expected data range, where ifthe read response is within the expected data range, data is readaccording to a first data read protocol or if the read response isoutside the expected data range, data is read according to a second dataread protocol performable by special-purpose hardware or software. Insuch a computer program, the second data read protocol may beperformable by special-purpose software, which may, for example, controlthe scan rate of a data read device performing the second data readprotocol at a reduced scan rate relative to the scan rate of a data readdevice performing the first data read protocol. In other embodiments,the special-purpose software may read data to be detected from adifferent location of the data read device under the second data readprotocol than under the first data read protocol. In other embodiments,the second data read protocol is performable by special-purposehardware, which may be controlled or operated by the computer program.Special purpose hardware may permit reading of data having a reducedsignal-to-noise ratio relative to data readable with general purposehardware.

With regard to the hardware and/or software used in the control ofdevices and systems for reading from data storage devices according tothe present embodiments, those having skill in the art will recognizethat the state of the art has progressed to the point where there islittle distinction left between hardware and software implementations ofaspects of such systems; the use of hardware or software is generally(but not always, in that in certain contexts the choice between hardwareand software can become significant) a design choice representing costvs. efficiency or implementation convenience tradeoffs. Those havingskill in the art will appreciate that there are various vehicles bywhich processes and/or systems described herein can be effected (e.g.,hardware, software, and/or firmware), and that the preferred vehiclewill vary with the context in which the processes are deployed. Forexample, if an implementer determines that speed and accuracy areparamount, the implementer may opt for a hardware and/or firmwarevehicle; alternatively, if flexibility is paramount, the implementer mayopt for a solely software implementation; or, yet again alternatively,the implementer may opt for some combination of hardware, software,and/or firmware. Hence, there are several possible vehicles by which theprocesses described herein may be effected, none of which is inherentlysuperior to the other in that any vehicle to be utilized is a choicedependent upon the context in which the vehicle will be deployed and thespecific concerns (e.g., speed, flexibility, or predictability) of theimplementer, any of which may vary.

In some embodiments, portions of the subject matter described herein maybe implemented via Application Specific Integrated Circuits (ASICs),Field Programmable Gate Arrays (FPGAs), digital signal processors(DSPs), or other integrated formats. However, those skilled in the artwill recognize that some aspects of the embodiments disclosed herein, inwhole or in part, can be equivalently implemented in standard integratedcircuits, as one or more computer programs running on one or morecomputers (e.g., as one or more programs running on one or more computersystems), as one or more programs running on one or more processors(e.g., as one or more programs running on one or more microprocessors),as firmware, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and/or firmwarewould be well within the capabilities of one of skill in the art inlight of this disclosure. In addition, those skilled in the art willappreciate that certain mechanisms of the subject matter describedherein are capable of being distributed as a program product in avariety of forms, and that an illustrative embodiment of the subjectmatter described herein applies equally regardless of the particulartype of signal bearing media used to actually carry out thedistribution. Examples of a signal bearing media include, but are notlimited to, the following: recordable type media such as floppy disks,hard disk drives, CD ROMs, digital tape, and computer memory; andtransmission type media such as digital and analog communication linksusing TDM or IP based communication links (e.g., links carryingpacketized data).

In a general sense, those skilled in the art will recognize that thevarious aspects described herein which can be implemented, individuallyand/or collectively, by a wide range of hardware, software, firmware, orany combination thereof can be viewed as being composed of various typesof “electrical circuitry.” Consequently, as used herein “electricalcircuitry” includes, but is not limited to, electrical circuitry havingat least one discrete electrical circuit, electrical circuitry having atleast one integrated circuit, electrical circuitry having at least oneapplication specific integrated circuit, electrical circuitry forming ageneral purpose computing device configured by a computer program (e.g.,a general purpose computer configured by a computer program which atleast partially carries out processes and/or devices described herein,or a microprocessor configured by a computer program which at leastpartially carries out processes and/or devices described herein),electrical circuitry forming a memory device (e.g., forms of randomaccess memory or an optical or ferromagnetic memory structure), and/orelectrical circuitry forming a communications device (e.g., a modem,communications switch, or optical-electrical equipment).

The foregoing detailed description has set forth various embodiments ofthe devices and/or processes via the use of block diagrams, flowcharts,and/or examples. Insofar as such block diagrams, flowcharts, and/orexamples contain one or more functions and/or operations, it will beimplicitly understood by those with skill in the art that each functionand/or operation within such block diagrams, flowcharts, or examples canbe implemented, individually and/or collectively, by a wide range ofhardware, software, firmware, or virtually any combination thereof.

Those skilled in the art will recognize that it is common within the artto describe devices for data storage and reading in the fashion setforth herein, and thereafter use standard engineering practices tointegrate such described devices and/or processes into systems includingdata storage devices as exemplified herein. That is, at least a portionof the devices and/or processes described herein can be integrated intoa system including a data storage device via a reasonable amount ofexperimentation. Those having skill in the art will recognize that suchsystems generally include one or more of a memory such as volatile andnon-volatile memory, processors such as microprocessors and digitalsignal processors, computational-supporting or associated entities suchas operating systems, user interfaces, drivers, sensors, actuators,applications programs, one or more interaction devices, such as dataports, control systems including feedback loops and control implementingactuators (e.g., devices for sensing position and/or velocity and/oracceleration or time-rate-of-change thereof; control motors for movingand/or adjusting components and/or quantities). A typical system may beimplemented utilizing any suitable available components, such as thosetypically found in appropriate computing/communication systems and/ordata storage and reading systems, combined with standard engineeringpractices.

The foregoing-described aspects depict different components containedwithin, or connected with, different other components. It is to beunderstood that such depicted architectures are merely exemplary, andthat in fact many other architectures can be implemented which achievethe same functionality. In a conceptual sense, any arrangement ofcomponents to achieve the same functionality is effectively “associated”such that the desired functionality is achieved. Hence, any twocomponents herein combined to achieve a particular functionality can beseen as “associated with” each other such that the desired functionalityis achieved, irrespective of architectures or intermediate components.Likewise, any two components so associated can also be viewed as being“operably connected”, or “operably coupled”, to each other to achievethe desired functionality.

While particular aspects of the present subject matter described hereinhave been shown and described, it will be obvious to those skilled inthe art that, based upon the teachings herein, changes and modificationsmay be made without departing from this subject matter described hereinand its broader aspects and, therefore, the appended claims are toencompass within their scope all such changes and modifications as arewithin the true spirit and scope of this subject matter describedherein. Furthermore, it is to be understood that the invention isdefined by the appended claims. It will be understood by those withinthe art that, in general, terms used herein, and especially in theappended claims (e.g., bodies of the appended claims) are generallyintended as “open” terms (e.g., the term “including” should beinterpreted as “including but not limited to,” the term “having” shouldbe interpreted as “having at least,” the term “includes” should beinterpreted as “includes but is not limited to,” etc.). It will befurther understood by those within the art that if a specific number ofan introduced claim recitation is intended, such an intent will beexplicitly recited in the claim, and in the absence of such recitationno such intent is present. For example, as an aid to understanding, thefollowing appended claims may contain usage of the introductory phrases“at least one” and “one or more” to introduce claim recitations.However, the use of such phrases should NOT be construed to imply thatthe introduction of a claim recitation by the indefinite articles “a” or“an” limits any particular claim containing such introduced claimrecitation to inventions containing only one such recitation, even whenthe same claim includes the introductory phrases “one or more” or “atleast one” and indefinite articles such as “a” or “an” (e.g., “a” and/or“an” should typically be interpreted to mean “at least one” and/or “oneor more”); the same holds true for the use of definite articles used tointroduce claim recitations. In addition, even if a specific number ofan introduced claim recitation is explicitly recited, those skilled inthe art will recognize that such recitation should typically beinterpreted to mean at least the recited number (e.g., the barerecitation of “two recitations,” without other modifiers, typicallymeans at least two recitations, or two or more recitations).Furthermore, in those instances where a convention analogous to “atleast one of A, B, and C, etc.” is used, in general such a constructionis intended in the sense of one having skill in the art would understandthe convention (e.g., “a system having at least one of A, B, and C”would include but not be limited to systems that have A alone, B alone,C alone, A and B together, A and C together, B and C together, and/or A,B, and C together). In those instances where a convention analogous to“at least one of A, B, or C, etc.” is used, in general such aconstruction is intended in the sense of one having skill in the artwould understand the convention (e.g., “a system having at least one ofA, B, or C” would include but not be limited to systems that have Aalone, B alone, C alone, A and B together, A and C together, B and Ctogether, and/or A, B, and C together).

Although the methods, devices, systems and approaches herein have beendescribed with reference to certain preferred embodiments, otherembodiments are possible. As illustrated by the foregoing examples,various choices of system configuration may be within the scope of theinvention. As has been discussed, the choice of system configuration maydepend on the intended application of the system, the environment inwhich the system is used, cost, personal preference or other factors.Data storage device design, manufacture, and control processes may bemodified to take into account choices of system components andconfiguration, and such modifications, as known to those of skill in thearts of data storage and retrieval structures and systems, fluid controlstructures, and electronics design and construction, may fall within thescope of the invention. Therefore, the full spirit or scope of theinvention is defined by the appended claims and is not to be limited tothe specific embodiments described herein.

1. A memory device comprising: a substrate; a data storage medium on thesubstrate; and machine readable data stored in the data storage mediumand having a first readability that is readable by a first type of dataread system, the machine readable data including: at least one firstportion having a readability modifiable by a limited expected lifetimeto a second readability that is not readable by the first type of dataread system; at least one second portion having a readability notmodifiable by the limited expected lifetime; and at least one thirdportion having a readability not modifiable by the limited expectedlifetime; wherein the at least one first portion contains read-controlinformation that causes data to be read from the at least one secondportion when the at least one first portion has the first readability,and causes data to be read from the at least one third portion when theat least one first portion has the second readability.
 2. The memorydevice of claim 1, wherein the limited expected lifetime is defined by alimited number of readings of the machine readable data from the memorydevice.
 3. The memory device of claim 1, wherein the limited expectedlifetime is defined by a limited number of uses of the memory device. 4.The memory device of claim 1, wherein the limited expected lifetime isdefined by a limited time interval following an initial use of thedevice.
 5. The memory device of claim 1, wherein machine readable datain the at least one first portion having the second readability has areduced signal-to-noise ratio relative to machine readable data havingthe first readability.
 6. The memory device of claim 1, wherein machinereadable data in the at least one first portion having the secondreadability has an increased bit error rate relative to machine readabledata having the first readability.
 7. The memory device of claim 1,wherein machine readable data in the at least one first portion havingthe second readability has a reduced redundancy relative to machinereadable data having the first readability.
 8. A memory devicecomprising: a substrate; a data storage medium on the substrate; andmachine readable data stored in the data storage medium and having afirst readability, at least a portion of the machine readable datahaving a readability that is modifiable to a second readability by alimited expected lifetime through degradation of at least one of thesubstrate or the data storage medium by at least one of light, heat,moisture, chemicals, an electrical field, or a magnetic field; whereinmachine readable data having the first readability is readable by afirst type of data read system and wherein machine readable data havingthe second readability is not readable by the first type of data readsystem.
 9. The memory device of claim 8, wherein readability of at leastone first portion of the machine readable data is modifiable by thelimited expected lifetime, wherein readability of at least one secondportion of the machine readable data is not modifiable by the limitedexpected lifetime, and wherein the at least one first portion containsread-support information needed for reading data of interest in the atleast one second portion.
 10. The memory device of claim 9, whereinmachine readable data in the at least one first portion having thesecond readability is substantially unreadable, and wherein additionalread-support information is stored in the at least one second portionand retrievable with a special purpose read system.
 11. The memorydevice of claim 10, wherein the additional read-support informationincludes a portion of the read-support information in the at least onefirst portion.
 12. The memory device of claim 11, wherein the portion ofthe read-support information is complementary to a residual portion ofthe read-support information readable from the at least one firstportion following modification of readability.
 13. The memory device ofclaim 10, wherein the additional read-support information is distributedamong multiple locations in the at least one second portion.
 14. Thememory device of claim 13, wherein additional read-support informationdistributed among the multiple locations is retrievable with the use ofindex information.